1. Field of the Invention
The present invention generally relates to a system and method for modifying bars and spaces in a bar code symbol. Specifically, the bars in a bar code are modified for applying the bar code symbol to a non-flat, or irregular surface. In particular, the present invention is directed to creating and reading a bar code symbol on an irregular surface by compensating for distortions caused by the non-flat or irregular surface. By creating a compensated bar code, by applying a compensated bar code symbol upon, and by reading a bar code symbol applied to a non-flat surface, bar codes may be now applied on and read from many surfaces heretofore unable to be bar coded.
2. Description of the Related Art
There is a great need in manufacturing to provide machine-readable information. Bar code technology is the most economical, popular means to provide that machine-readable data. Bar code symbologies of various types have been developed to meet the specific needs of different activities including manufacturing warehouse storage, shipping, and merchandising.
In its simplest form, a bar code is a series of printed vertical bars and spaces, applied in one way or another to a surface, that are read by a scanner as digital information. In any case, the successful reading of a bar code relies on several factors. Most scanners “read” by projecting many thousands of pulses of light in a line across the code. The bars and spaces are of regular widths (all multiples of a Unit-Measure or X-Dimension). Bars and spaces are defined by a degree of contrast, and absorb or reflect these pulses accordingly. The scanner tallies these “yes” or “no” signals as binary digits to be translated by the scanner's software into the information encoded.
In order for this to happen successfully, the scanner's projected pulses of light must meet the surface upon which the bar code is imprinted at a constant angle, so that a constant relationship exists between the width of a bar or space and the number of pulses of light it reflects. This means that the bar code must be printed on a flat surface. Of course, not every surface is flat and, as a result, there are obvious limits to where (and to what) a bar code can be applied.
The Uniform Code Council (UCC), part of the UCC/EAN writes the global bar code standards for UPC and EAN bar codes and has addressed various readability issues. The most robust codes, (binary codes), have only two bar thicknesses (“Thick” and “Thin”) and can be read successfully despite bar width variations of up to 50%. The bars of a standard UPC, however, have four distinct thicknesses and are much less tolerant of dimensional error. Because the error allowance is a percentage, the code becomes more and more prone to readability problems as its size decreases. Thus, the UCC specifies the minimum width of a UPC, for example, as just over 1 inch. In a similar way, the UCC standard for maximum curve across the bars of a bar code is a function of the size of the bar code. According to the UCC, a bar code may occupy no greater than 60° of the circumference of a cylinder. For this reason, typically, the smallest cylinder to which a UPC can be applied is just over 6″ in circumference.
There are wide variety of other technical challenges to applying and reading bar codes on products. Many products on a productive line have irregular non-flat surfaces, such as ribbed, cylindrical or spherical. It is quite difficult to apply a bar code to these surfaces that are not flat. That is, if a standard bar code is applied to an irregular surface, the bars of the bar code appear to the scanner to be distorted when they are applied to these surfaces. The spaces between these bars will necessarily also be distorted. Such distortions can make the bar code either subject to reading errors or entirely unreadable.
Accordingly, there is therefore a great need in the art for a device and way by which to apply bars and spaces of a bar code to an irregular, or non-flat surface. There is a concomitant need in the art for a way by which to read bar codes from an irregular or non-flat surface.
Accordingly, there is now provided with this invention an improved method and system for effectively overcoming the difficult and longstanding problems inherent in creating, applying, and reading bar codes on irregular, non-flat surfaces. These problems have been solved in a highly effective way to compensate for distortions caused by these surfaces.